Having read so much about this I honestly think schools needs closing:
According to science magazine
www.sciencemag.org if a school has had a case and closes this is a reactive response:
There have been a number of studies that have looked at reactive closures. These analyses, including a paper in Nature in 2006 using math models [of an influenza pandemic], typically find that such reactive school closures for a moderately transmissible pathogen reduces the cumulative infection rate by about 25% and delay the peak of the epidemic [in that region] by about 2 weeks. When you postpone the peak, you also typically flatten the epidemic and space out your cases. This has value. It means that the incidence on any given day is lower, so we don’t overburden our health care system.
this is further down the article about proactive closures:
Q: How about proactive school closures, before there are any infections associated with a school? Are they helpful?
A: Proactive school closures—closing schools before there’s a case there—have been shown to be one of the most powerful nonpharmaceutical interventions that we can deploy. Proactive school closures work like reactive school closures not just because they get the children, the little vectors, removed from circulation. It’s not just about keeping the kids safe. It’s keeping the whole community safe. When you close the schools, you reduce the mixing of the adults—parents dropping off at the school, the teachers being present. When you close the schools, you effectively require the parents to stay home.
There was a wonderful paper published that analyzed data regarding the Spanish flu in 1918, examining proactive versus reactive school closures. When did [regional] authorities close the schools relative to when the epidemic was spiking? What they found was that proactive school closing saved substantial numbers of lives. St. Louis closed the schools about a day in advance of the epidemic spiking, for 143 days. Pittsburgh closed 7 days after the peak and only for 53 days. And the death rate for the epidemic in St. Louis was roughly one-third as high as in Pittsburgh. These things work.